Олег, "7" уже означает "every day"

+grumbler

Oleg is right - for some reason, we tend to use both together: https://www.google.com/?gws_rd=ssl#q=%22open+every+day,+24/7%22. Only it should be EVERY DAY (separate). EVERYDAY is an adjective.

Interestingly, even google tries to correct to everyday, but almost everywhere comma is missing. I guess, this indicates, in some degree, luck of education.

No, grumbler, it's because some people actually consider both elements as one whole expression, so they naturally don't separate them with a comma. That's what I was trying to explain)